Color liquid crystal display device

ABSTRACT

A color liquid crystal display device includes a liquid crystal display element and a backlight unit. The liquid crystal display element includes a color filter having a red filter segment, a green filter segment, and a blue filter segment. The red filter segment is prepared from a red photosensitive resin composition which includes a pigment combination, an alkali-soluble resin, a compound having an ethylenic group, and a photoinitiator. The pigment combination includes an azo-based red pigment and an anthraquinone-based red pigment. A weight ratio of the azo-based red pigment to the anthraquinone-based red pigment ranges from 20/80 to 80/20. The backlight unit is coupled to the liquid crystal display element and has a color temperature ranging from 6,000 K to 20,000 K.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 099130036,filed Sep. 6, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a color liquid crystal display device, moreparticularly to a color liquid crystal display device having highbrightness and high contrast.

2. Description of the Related Art

Recently, liquid crystal display devices have been increasinglydeveloped due to their characteristics, such as light weight, thinprofile, and power saving.

It is desirable to provide a liquid crystal display device having highbrightness and high contrast.

JP 10-148712 discloses a color resist composition for a color filter ofa liquid crystal display device. An anthraquinone-based red pigment suchas C.I. Pigment Red 177 is used in a red pixel of the color filter. Thered pigment is mechanically micronized to improve the dispersionthereof, such that the contrast of a liquid crystal display device canbe increased thereby. However, the brightness of the color filter cannot be effectively enhanced due to the spectral properties of the redpigment. Moreover, in JP 10-148712, an azo-based red pigment such asC.I. Pigment Red 166 is mixed with C.I. Pigment Red 177 and yellowpigments so as to improve color characteristics. Although the colorreproduction area of the color filter is expanded, the contrast can notbe enhanced.

In JP 11-231516 and JP 2002-328217, C.I. Pigment Red 254, adiketo-pyrrolopyrrole-based red pigment, is used. Compared to C.I.Pigment red 177, the transmission spectrum at about 600 nm of C.I.Pigment Red 254 shifts toward shorter wavelength, and the red absorptionof the backlight is reduced so as to enhance the brightness. However,the cohesion among the micronized particles of C.I. Pigment Red 254 istoo strong. Therefore, it is difficult to disperse the micronizedparticles of C.I. Pigment Red 254, such that the contrast can not beenhanced.

Therefore, it is still required in the art to provide a color liquidcrystal display device having both high brightness and high contrast.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a color liquid crystaldisplay device having high brightness and high contrast.

The color liquid crystal display device according to this inventionincludes a liquid crystal display element and a backlight unit. Theliquid crystal display element includes a color filter having a redfilter segment, a green filter segment, and a blue filter segment. Thered filter segment is prepared from a red photosensitive resincomposition which includes a pigment combination, an alkali-solubleresin, a compound having an ethylenic group, and a photoinitiator. Thepigment combination includes an azo-based red pigment and ananthraquinone-based red pigment. A weight ratio of the azo-based redpigment to the anthraquinone-based red pigment ranges from 20/80 to80/20. The backlight unit is coupled to the liquid crystal displayelement and has a color temperature ranging from 6,000 K to 20,000 K.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiments with reference to the accompanying drawings, of which:

FIG. 1 is a fragmentary schematic view of a preferred embodiment of acolor liquid crystal display device according to this invention; and

FIG. 2 is a sectional view of a white light emitting diode used in thepreferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the preferred embodiment of the color liquidcrystal display device according to this invention includes a liquidcrystal display element 10 and a backlight unit 20.

The liquid crystal display element 10 includes a first substrate 13, asecond substrate 14 spaced apart from the first substrate 13, a colorfilter 11 coupled to the first substrate 13, two alignment layers 15respectively disposed on the color filter 11 and the second substrate 14and facing toward each other, liquid crystal 12 disposed between thealignment layers 15, and two polarizers 16 respectively coupled to thefirst and second substrates 13, 14 and distal from the liquid crystal12. The first substrate 13 is a color filter side substrate, and thesecond substrate 14 is a thin film transistor side substrate. Since themethod for manufacturing the liquid crystal display element 10 is wellknown in the art, it is not described in detail herein.

The color filter 11 has at least one red filter segment, at least onegreen filter segment, and at least one blue filter segment. The redfilter segment is made of a red photosensitive resin composition whichincludes (A) a pigment combination, (B) an alkali-soluble resin, (C) acompound having an ethylenic group, (D) a photoinitiator, and (E) anorganic solvent. The pigment combination includes (A-1) an azo-based redpigment and (A-2) an anthraquinone-based red pigment. A weight ratio ofthe azo-based red pigment to the anthraquinone-based red pigment rangesfrom 20/80 to 80/20.

The pigment combination is used in an amount ranging generally from 100to 800 parts by weight, preferably from 150 to 600 parts by weight, andmore preferably from 200 to 500 parts by weight, based on 100 parts byweight of the alkali-soluble resin.

Specifically, the azo-based red pigment is used in an amount ranginggenerally from 20 to 250 parts by weight, preferably from 40 to 200parts by weight, and more preferably from 60 to 150 parts by weight,based on 100 parts by weight of the alkali-soluble resin. Theanthraquinone-based red pigment is used in an amount ranging generallyfrom 20 to 250 parts by weight, preferably from 40 to 200 parts byweight, and more preferably from 60 to 150 parts by weight, based on 100parts by weight of the alkali-soluble resin.

As described above, the weight ratio of the azo-based red pigment to theanthraquinone-based red pigment ranges from 20/80 to 80/20. When theweight ratio of the azo-based red pigment to the anthraquinone-based redpigment is less than 20/80, the contrast of the color liquid crystaldisplay device can not be enhanced. When the weight ratio of theazo-based red pigment to the anthraquinone-based red pigment is morethan 80/20, the brightness of the color liquid crystal display devicemay be reduced. Preferably, the weight ratio of the azo-based redpigment to the anthraquinone-based red pigment ranges from 30/70 to80/20. More preferably, the weight ratio of the azo-based red pigment tothe anthraquinone-based red pigment ranges from 40/60 to 80/20.

Preferably, examples of the azo-based red pigment include, but are notlimited to, C.I. Pigment Red 144, C.I. Pigment Red 166, C.I. Pigment Red214, C.I. Pigment Red 220, C.I. Pigment Red 221, C.I. Pigment Red 242,C.I. Pigment Red 248, C.I. Pigment Red 262, and combinations thereof.Examples of the anthraquinone-based red pigment include, but are notlimited to, C.I. Pigment Red 83, C.I. Pigment Red 89, P.I. Pigment Red177, and combinations thereof. More preferably, the azo-based redpigment is C.I. Pigment Red 166, P.I. Pigment Red 242, or a combinationthereof. The anthraquinone-based red pigment is C.I. Pigment Red 89,C.I. Pigment Red 177, or a combination thereof.

The mean particle size of the primary particles of the azo-based redpigment and the anthraquinone-based red pigment ranges generally from 10to 200 nm, preferably from 20 to 150 nm, and more preferably from 30 to100 nm.

The micronization of the mean particle size of the primary particles ofthe azo-based red pigment and the anthraquinone-based red pigment can beconducted by a grinding method in which the pigments are mechanicallyground, a precipitation method in which the pigments are dissolved in agood solvent and then are precipitated using a poor solvent, or asynthetic precipitation in which the pigments of finer particle size areproduced in the synthesis process of the pigments.

The pigment combination can be used in combination with a dispersant, ifnecessary. Examples of the dispersant include, but are not limited to,cationic surfactants, anionic surfactants, nonionic surfactants,amphoteric surfactants, silicone-based surfactants, and fluorine-basedsurfactants. Examples of the surfactants include polyethylene oxidealkyl ethers, such as polyethylene oxide dodecyl ether, polyethyleneoxide stearoyl ether, polyethylene oxide oleyl ether, or the like;polyethylene oxide alkyl phenyl ethers, such as polyethylene oxide octylphenyl ether, polyethylene oxide nonyl phenyl ether, or the like;polyethylene glycol diesters, such as polyethylene glycol dilaurate,polyethylene glycol distearate, or the like; sorbitan fatty acid esters;fatty acid modified polyesters; tertiary amine modified polyurethanes;or the like. Examples of the commercial surfactants include KPmanufactured by Shin-Etsu Chemical Col, Ltd., SF-8427 manufactured byToray Dow Corning Silicon, Polyflow manufactured by Kyoeisha ChemicalCo., Ltd., F-Top manufactured by Tochem Products Co., Ltd., Megafacmanufactured by Dainippon Ink and Chemicals, Incorporated, Fluorademanufactured by Sumitomo 3M, Asahi Guard and Surflon both manufacturedby Asahi Glass, or the like. The above examples of the surfactant can beused alone or in combinations thereof.

An additional red pigment and/or a yellow pigment can be added into thepigment combination so as to adjust the chromaticity of the pigmentcombination. Examples of the additional red pigment include, but are notlimited to, quinacridones, perylenes, pyranthrene-8,16-diones, andcombinations thereof. Examples of the yellow pigment include, but arenot limited to, isoindoles, quinaphthalones, anthraquinones, andcombinations thereof. Preferably, the yellow pigment is selected fromquinaphthalones. More preferably, the yellow pigment is selected fromC.I. Pigment Yellow 1, C.I. Pigment Yellow 3, C.I. Pigment Yellow 10,C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14,C.I. Pigment Yellow 17, C.I. Pigment Yellow 20, C.I. Pigment Yellow 24,C.I. Pigment Yellow 31, C.I. Pigment Yellow 55, C.I. Pigment Yellow 81,C.I. Pigment Yellow 83, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94,C.I. Pigment Yellow 97, C.I. Pigment Yellow 109, C.I. Pigment Yellow110, C.I. Pigment Yellow 128, C.I. Pigment Yellow 138, C.I. PigmentYellow 139, C.I. Pigment Yellow 150, C.I. Pigment Yellow 153, C.I.Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. Pigment Yellow 166,C.I. Pigment Yellow 167, C.I. Pigment Yellow 168, C.I. Pigment Yellow180, C.I. Pigment Yellow 185, C.I. Pigment Yellow 211, C.I. PigmentYellow 219, or the like. These yellow pigments can be used alone or incombinations thereof. The yellow pigment is preferably selected fromC.I. Pigment Yellow 83, C.I. Pigment Yellow 138, C.I. Pigment Yellow139, C.I. Pigment Yellow 150, C.I. Pigment Yellow 185, C.I. PigmentYellow 219, and combinations thereof in consideration of color purityand transparency.

The additional red pigment is used in an amount ranging generally from 5to 100 parts by weight, preferably from 10 to 80 parts by weight, andmore preferably from 15 to 60 parts by weight, based on 100 parts byweight of the alkali-soluble resin. The yellow pigment is used in anamount ranging generally from 5 to 100 parts by weight, preferably from10 to 80 parts by weight, and more preferably from 15 to 60 parts byweight, based on 100 parts by weight of the alkali-soluble resin.

The alkali-soluble resin is obtained by subjecting an ethylenicallyunsaturated monomer having one or more carboxyl groups and anothercopolymerizable ethylenically unsaturated monomer to conduct acopolymerization. Preferably, the amounts of the ethylenicallyunsaturated monomer having one or more carboxyl groups and the anothercopolymerizable ethylenically unsaturated monomer used in thecopolymerization reaction are 50-95 parts by weight and 5-50 parts byweight, respectively, based on 100 parts by weight of the sum of theethylenically unsaturated monomer having one or more carboxyl groups andthe another copolymerizable ethylenically unsaturated monomer.

Examples of the aforementioned ethylenically unsaturated monomer havingone or more carboxyl groups include, but are not limited to, unsaturatedmonocarboxylic acids, such as acrylic acid, methacrylic acid, butenoicacid, α-chloroacrylic acid, ethacrylic acid, cinnamic acid,2-acryloylethoxy succinate, 2-methacryloylethoxy succinate, or the like;unsaturated dicarboxylic acids and/or anhydrides thereof, such as maleicacid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride,citraconic acid, citraconic anhydride, or the like; and unsaturatedpolycarboxylic acids having at least three carboxyl groups in themolecules and/or anhydrides thereof; or the like. Preferably, theethylenically unsaturated monomer having one or more carboxyl groups isselected from acrylic acid, methacrylic acid, 2-acryloylethoxysuccinate, and 2-methacryloylethoxy succinate. More preferably, theethylenically unsaturated monomer having one or more carboxyl groups isselected from 2-acryloylethoxy succinate and 2-methacryloylethoxysuccinate. The ethylenically unsaturated monomer having one or morecarboxyl groups is used for increasing the pigment dispersion, enhancingthe development speed, and reducing the residue.

Examples of the another copolymerizable ethylenically unsaturatedmonomer include, but are not limited to, vinyl aromatic compounds, suchas styrene, α-methyl styrene, o-vinyl toluene, p-chlorostyrene,methoxystyrene, or the N-o-hydroxyphenylmaleimide,N-m-hydroxyphenylmaleimide, N-p-hydroxyphenylmaleimide,N-o-methylphenylmaleimide, N-m-methylphenylmaleimide,N-p-methylphenylmaleimide, N-o-methoxyphenylmaleimide,N-m-methoxyphenylmaleimide, N-p-methoxyphenylmaleimide,N-cyclohexylmaleimide, or the like; unsaturated carboxylates, such asmethyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, n-propyl acrylate, n-propyl methacrylate, iso-propylacrylate, iso-propyl methacrylate, n-butyl acrylate, n-butylmethacrylate, iso-butyl acrylate, iso-butyl methacrylate, sec-butylacrylate, sec-butyl methacrylate, tert-butyl acrylate, tert-butylmethacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropylacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate,2-hydroxybutyl methacrylate, 3-hydroxybutyl acrylate, 3-hydroxybutylmethacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate,allyl acrylate, allyl methacrylate, benzyl acrylate, benzylmethacrylate, phenyl acrylate, phenyl methacrylate, methoxy triethyleneglycol acrylate, methoxy triethylene glycol methacrylate, laurylmethacrylate, tetradecyl methacrylate, cetyl methacrylate, octadecylmethacrylate, eicosyl methacrylate, docosyl methacrylate,dicyclopentenyloxyethyl acrylate, or the like; unsaturated amino alkylcarboxylates, such as N,N-dimethyl aminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethyl aminopropyl acrylate, N,N-dimethylaminopropyl methacrylate, N,N-dibutyl aminopropyl acrylate, or the like;unsaturated glycidyl carboxylates, such as glycidyl acrylate, glycidylmethacrylate, or the like; vinyl carboxylates, such as vinyl acetate,vinyl propionate, vinyl butyrate, or the like; unsaturated ethers, suchas vinyl methyl ether, vinyl ethyl ether, allyl glycidyl ether,methallyl glycidyl ether, or the like; vinyl cyanides, such asacrylonitrile, methyl acrylonitrile, α-chloroacrylonitrile, vinylidenecyanide, or the like; unsaturated amides, such as acrylamide,methacrylamide, α-chloroacrylamide, N-hydroxyethyl acrylamide,N-hydroxyethyl methacrylamide, or the like; and aliphatic conjugatedienes, such as 1,3-butadiene, iso-propylene, chloroprene, or the like.

Preferably, the another copolymerizable ethylenically unsaturatedmonomer is selected from styrene, N-phenylmaleimide, methyl acrylate,methyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethylmethacrylate, benzyl acrylate, benzyl methacrylate, anddicyclopentenyloxyethyl acrylate.

Examples of the solvent suitable for preparing the alkali-soluble resininclude, but are not limited to, (poly)alkylene glycol monoalkyl ethers,such as ethylene glycol methyl ether, ethylene glycol ethyl ether,diethylene glycol methyl ether, diethylene glycol ethyl ether,diethylene glycol n-propyl ether, diethylene glycol n-butyl ether,triethylene glycol methyl ether, triethylene glycol ethyl ether,propylene glycol methyl ether, propylene glycol ethyl ether, dipropyleneglycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycoln-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycolmethyl ether, tripropylene glycol ethyl ether, or the like;(poly)alkylene glycol monoalkyl ether acetates, such as ethylene glycolmethyl ether acetate, ethylene glycol ethyl ether acetate, propyleneglycol methyl ether acetate, propylene glycol ethyl ether acetate, orthe like; other ethers, such as diethylene glycol dimethyl ether,diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether,tetrahydrofuran, or the like; ketones, such as methyl ethyl ketone,cyclohexanone, 2-heptanone, 3-heptanone, or the like; alkyl lactate,such as methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, or thelike; other esters, such as methyl 2-hydroxy-2-methylpropionate, ethyl2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, methyl 3-ethoxypropionate, ethyl3-ethoxypropionate, ethyl ethoxy acetate, ethyl hydroxy acetate, methyl2-hydroxy-3-methylbutyrate, 3-methyl-3-methoxybutyl acetate,3-methyl-3-methoxybutyl propionate, ethyl acetate, n-propyl acetate,iso-propyl acetate, n-butyl acetate, iso-butyl acetate, n-amyl acetate,iso-amyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate,iso-propyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate,n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl2-oxobutyrate, or the like; aromatic hydrocarbons, such as toluene,xylene, or the like; and carboxylic acid amide, such asN-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, orthe like. Preferably, the solvent is selected from propylene glycolmethyl ether acetate and ethyl 3-ethoxypropionate. The aforesaidexamples of the solvent can be used alone or in admixture of two or morethereof.

The initiator used for preparing the alkali-soluble resin is a freeradical polymerization initiator, examples of which include, but are notlimited to, azo compounds, such as 2,2′-azobisisobutyronitrile,2,2′-azobis-(2,4-dimethylvaleronitrile),2,2′-azobis-(4-methoxy-2,4-dimethylvaleronitrile),2,2′-azobis-2-methylbutyronitrile, or the like; and peroxides, such asbenzoyl peroxide, or the like.

The compound having an ethylenic group used in the present invention isa compound having one or more ethylenically unsaturated groups.

Examples of the compound having one ethylenically unsaturated groupinclude, but are not limited to, acrylamide, (meth) acryloylmorpholine,7-amino-3,7-dimethyloctyl(meth)acrylate, iso-butoxymethyl(meth)acrylamide, iso-bornyloxyethyl (meth)acrylate, iso-bornyl(meth)acrylate,2-ethylhexyl (meth)acrylate, ethyl diethylene glycol (meth)acrylate,t-octyl(meth) acrylamide, diacetone (meth) acrylamide,dimethylaminoethyl(meth) acrylate, dodecyl (meth)acrylate,dicyclopentenyloxyethyl(meth)acrylate, dicyclopentenyl(meth)acrylate,N,N-dimethyl (meth) acrylamide, tetrachlorophenyl(meth)acrylate,2-tetrachlorophenoxy ethyl(meth)acrylate,tetrahydrofurfuryl(meth)acrylate, tetrabromophenyl (meth)acrylate,2-tetrabromophenoxyethyl(meth)acrylate,2-trichlorophenoxyethyl(meth)acrylate, tribromophenyl (meth)acrylate,2-tribromophenoxyethyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate,2-hydroxypropyl (meth)acrylate, vinylcaprolactam, N-vinylpyrrolidone,phenoxyethyl(meth)acrylate, pentachlorophenyl (meth)acrylate,pentabromophenyl(meth)acrylate, polyethylene glycol mono(meth)acrylate,polypropylene glycol mono(meth)acrylate, bornyl(meth)acrylate, or like.

Examples of the compound having two or more ethylenically unsaturatedgroups include, but are not limited to, ethylene glycoldi(meth)acrylate, dicyclopentenyl di(meth)acrylate, triethylene glycoldiacrylate, tetraethylene glycol di(meth)acrylate, tri(2-hydroxyethyl)isocyanate di(meth)acrylate, tri(2-hydroxyethyl) isocyanatetri(meth)acrylate, caprolactone-modified tri(2-hydroxyethyl) isocyanatetri(meth)acrylate, trimethylolpropyl tri(meth)acrylate, ethylene oxide(hereinafter abbreviated as EO) modified trimethylolpropyltri(meth)acrylate, propylene oxide (hereinafter abbreviated as PO)modified trimethylolpropyl tri(meth)acrylate, tripropylene glycoldi(meth)acrylate, neo-pentyl glycol di(meth)acrylate, 1,4-butanedioldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritoltri(meth)acrylate, pentaerythritoltetra(meth)acrylate, polyesterdi(meth)acrylate, polyethylene glycol di(meth)acrylate,dipentaerythritolhexa(meth)acrylate, dipentaerythritolpenta(meth)acrylate, dipentaerythritol tetra(meth)acrylate,caprolactone-modified dipentaerythritol hexa(meth)acrylate,caprolactone-modified dipentaerythritol penta(meth)acrylate,ditrimethylolpropyl tetra(meth)acrylate, EO-modified bisphenol Adi(meth)acrylate, PO-modified bisphenol A di(meth)acrylate, EO-modifiedhydrogenated bisphenol A di(meth)acrylate, PO-modified hydrogenatedbisphenol A di(meth)acrylate, PO-modified glycerol triacrylate,EO-modified bisphenol F di(meth)acrylate, phenol novolac polyglycidylether (meth)acrylate, or the like.

Preferably, the compound having an ethylenic group is selected fromtrimethylolpropyl triacrylate, EO-modified trimethylolpropyltriacrylate, PO-modified trimethylolpropyl triacrylate, pentaerythritoltriacrylate, pentaerythritol tetracrylate, dipentaerythritolhexaacrylate, dipentaerythritol pentaacrylate, dipentaerythritoltetraacrylate, caprolactone-modified dipentaerythritol hexaacrylate,ditrimethylolpropyl tetraacrylate, and PO-modified glycerol triacrylate.The aforesaid examples of the compound having an ethylenic group can beused alone or in admixture of two or more thereof.

The compound having an ethylenic group is used in an amount ranginggenerally from 10 to 500 parts by weight, preferably from 30 to 400parts by weight, and more preferably from 50 to 300 parts by weight,based on 100 parts by weight of the alkali-soluble resin.

The photoinitiator suitable for the present invention is selected fromO-acyloxime compounds, triazine compounds, acetophenone compounds,biimidazole compounds, or benzophenone compounds. The photoinitiator isused in an amount ranging generally from 2 to 200 parts by weight,preferably from 5 to 180 parts by weight, and more preferably from 10 to150 parts by weight, based on 100 parts by weight of the alkali-solubleresin.

Examples of the O-acyloxime compounds include, but are not limited to,1-[4-(phenylthio)phenyl]-heptane-1,2-dione 2-(O-benzoyloxime),1-[4-(phenylthio)phenyl]-octane-1,2-dione 2-(O-benzoyloxime),1-[4-(benzoyl)phenyl]-heptane-1,2-dione 2-(O-benzoyloxime),1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethylketo1-(O-acetyloxime),1-[9-ethyl-6-(3-methylbenzoyl)-9H-carbazol-3-yl]-ethylketo1-(O-acetyloxime), 1-[9-ethyl-6-benzoyl-9H-carbazol-3-yl]-ethylketo1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-4-tetrahydrofurylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-4-tetrapyranylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-5-tetrafurylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-5-tetrapyranylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-4-tetrafurylmethoxybenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-4-tetrapyranylmethoxybenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-5-tetrafurylmethoxybenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-5-tetrapyranylmethoxybenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolyl)benzoyl}-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolyl)methoxybenzoyl}-9H-carbazol-3-yl]-1-(O-acetyloxime), or the like.

Examples of the triazine compounds include, but are not limited to,2,4-bis(trichloromethyl)-6-(p-methoxy)styryl-s-triazine,2,4-bis(trichloromethyl)-6-(1-p-dimethylaminophenyl-1,3-butadienyl)-s-triazine,2-trichloromethyl-4-amino-6-(p-methoxy)styryl-s-triazine, or the like.

Examples of the acetophenone compounds include, but are not limited to,p-dimethylaminoacetophenone, α,α′-dimethoxyazoxyacetophenone,2,2′-dimethyl-2-phenylacetophenone, p-methoxyacetophenone,2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propan one,2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, or thelike.

Examples of the biimidazole compounds include, but are not limited to,2,2′-bis(o-chlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-fluorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-methylphenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-methoxyphenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-ethylphenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(p-methoxyphenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(2,2′,4,4′-tetramethoxyphenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(2-chlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(2,4-dichlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole, or thelike.

Examples of the benzophenone compounds include, but are not limited to,thioxanthone, 2,4-diethylthioxanthone, thioxanthone-4-sulfone,benzophenone, 4,4′-bis(dimethylamino)benzophenone,4,4′-bis(diethylamino)benzophenone, or the like.

Preferably, the photoinitiator is selected from1-[4-(phenylthio)phenyl]-octane-1,2-dione 2-(O-benzoyloxime),1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethylketo1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-(2-methyl-4-tetrahydrofurylmethoxybenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime),ethylketo-1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolyl)methoxybenzoyl}-9H-carbazol-3-yl]-1-(O-acetyloxime),2,4-bis(trichloromethyl)-6-(p-methoxy)styryl-s-triazine,2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone,2,2′-bis(2,4-dichlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole, and4,4′-bis(diethylamino)benzophenone.

In addition to the aforesaid photoinitiators, other initiators can befurther added into the red photosensitive resin composition of thepresent invention. Examples of the other initiators include, but are notlimited to, α-diketone compounds, such as benzil, acetyl, or the like;acyloin compounds, such as benzoin, or the like; acyloin ethercompounds, such as benzoin methyl ether, benzoin ethyl ether, benzoinisopropyl ether, or the like; acylphosphine oxide compounds, such as2,4,6-trimethylbenzoyl diphenylphosphine oxide,bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethyl benzyl phosphine oxide, orthe like; quinone compounds, such as anthraquinone, 1,4-naphthoquinone,or the like; halide compounds, such as phenacyl chloride, tribromomethylphenylsulfone, tris(trichloromethyl)-s-triazine, or the like; andperoxide compounds, such as di-tert-butyl peroxide; or the like.

All the above components except the pigment combination are generallydissolved in an appropriate organic solvent to prepare a liquidcomposition, and the pigment combination is then mixed with the liquidcomposition to prepare the red photosensitive resin composition. Anysolvents, which are inert to and can disperse or dissolve thealkali-soluble resin, the compound having an ethylenic group, and thephotoinitiator and which have appropriate volatility, can be used.

The organic solvent for preparing the red photosensitive resincomposition is used in an amount ranging generally from 500 to 5,000parts by weight, preferably from 800 to 4,500 parts by weight, and morepreferably from 1,000 to 4,000 parts by weight, based on 100 parts byweight of the alkali-soluble resin.

The organic solvent suitable for preparing the red photosensitive resincomposition can be selected from the examples of the solvent forpreparing the alkali-soluble resin. Preferably, the organic solventsuitable for preparing the red photosensitive resin composition ispropylene glycol methyl ether acetate or ethyl 3-ethoxypropionate. Theexamples of the organic solvent suitable for preparing the redphotosensitive resin composition can be used alone or in combinationsthereof.

The red photosensitive resin composition in the present invention cancontain other additives, such as fillers, polymers other than thealkali-soluble resin, adhesion agents, antioxidants, UV absorbents,anti-coagulants, or the like according to the specific requirements forthe physical and/or chemical properties of the red filter segment madefrom the red photosensitive resin composition.

Examples of the fillers include glass, alumina, or the like. Examples ofthe polymers other than the alkali-soluble resin include polyvinylalcohol, polyethylene glycol monoalkyl ether, polyfluoro alkyl acrylate,or the like. Examples of the adhesion agents includevinyltrimethoxysilane, vinyltriethoxysilane,vinyltris(2-methoxyethoxy)silane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane,3-glycidyloxypropylmethyldimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane,3-methacryl oxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane,or the like. Examples of the antioxidants include2,2-thiobis(4-methyl-6-t-butylphenol), 2,6-di-t-butylphenol, or thelike. Examples of the UV absorbents include2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole,alkoxybenzophenone, or the like. Examples of the anti-coagulants includesodium polyacrylate, or the like.

The other additives are used in an amount ranging generally from 0 to 10parts by weight, preferably from 0 to 6 parts by weight, and morepreferably from 0 to 3 parts by weight, based on 100 parts by weight ofthe alkali-soluble resin.

The green filter segment and the blue filter segment in the presentinvention can be made of a conventional green photosensitive resincomposition and a conventional blue photosensitive resin composition,respectively. The components of the green and blue photosensitive resincompositions are substantially identical to those of the redphotosensitive resin composition except that instead of the pigmentcombination used in the red photosensitive resin composition, a greenpigment is used in the green photosensitive resin composition whereas ablue pigment is used in the blue photosensitive resin composition.Examples of the green pigment include, but are not limited to, C.I.Pigment Green 07, 36, 37, 58, alone or in combinations thereof, combinedwith C.I. Pigment Yellow 12, 13, 14, 17, 20, 24, 31, 55, 83, 93, 109,110, 128, 138, 139, 150, 153, 154, 155, 166, 168, 180, 185, 211, 219,alone or in combinations thereof. Preferably, the green pigmentincludes, but it not limited to, C.I. Pigment Green 07, 36, 58, alone orin combinations thereof, with C.I. Pigment Yellow 13, 138, 139, 150,alone or in combinations thereof. Examples of the blue pigment include,but are not limited to, C.I. Pigment Blue 15:1, 15:2, 15:3, 15:4, 15:6,21, 22, 60, 64, alone or in combinations thereof, combined with C.I.Pigment Purple 19, 23, 29, 32, 33, 36, 37, 38, 40, 50, alone or incombinations thereof. Preferably, the blue pigment is C.I. Pigment Blue15:6 combined with C.I. Pigment Purple 23. In the following illustrativeexamples, the green pigment is C.I. Pigment Green 58 combined with C.I.Pigment Yellow 150, and the blue pigment is C.I. Pigment Blue 15combined with C.I. Pigment Purple 23.

The red photosensitive resin composition in a liquid state for the colorfilter in the present invention can be formed by blending thealkali-soluble resin, the compound having an ethylenic group, and thephotoinitiator with the pigment combination in the organic solvent usinga mixer. The red photosensitive resin composition is coated on asubstrate by a spin coating method, a knife coating method, an ink-jetcoating method, a roller coating method, or the like, and is then driedunder reduced pressure to remove most of the solvent. After completelyevaporating the residual solvent by pre-baking, a coating film isformed. Operation conditions for the drying under reduced pressure andthe pre-baking depend on kinds and amounts of the components used in thered photosensitive resin composition. In general, the drying underreduced pressure is carried out at a pressure from 0 to 200 mm Hg for aperiod from 1 to 60 seconds. The pre-baking is carried out at atemperature from 70° C. to 110° C. for a period from 1 to 15 minutes.The coating film is then exposed to UV light through a specific photomask, and is developed in a developer solution at a temperature of 23±2°C. for a period from 15 seconds to 5 minutes to dissolve and remove theunexposed portions of the coating film so as to obtain a desiredpattern. The substrate with the desired pattern of the coating film iswashed with water, is dried with compressed air or compressed nitrogen,and is heated at a temperature from 100 to 280° C. for a period of 1 to15 minutes in a heating device, such as a hot plate or an oven so as toremove evaporative components and to subject the unreacted ethyleniccompound contained in the coating film to conduct a heat curingreaction. The red filter segment can be obtained thereby. The green andblue filter segments can be obtained using the green and bluephotosensitive resin compositions, respectively, following the procedurefor making the red filter segment. A color filter can be obtainedthereby.

The UV light used for the exposure of the coating film can be g line, hline, i line, or the like. The UV lamp for providing the UV light is a(ultra)high-pressure mercury lamp or a metal halide lamp. The substrateused to form the color filter is made from bare glass, soda glass, Pyrexglass, silica glass, or any one of these glass coated with a transparentconductive film, or a transparent electrode substrate used in solidstate image pick up devices. A black matrix is formed on the substrateto separate each color pixel element.

The developer solution is preferably an alkali aqueous solution ofsodium hydroxide, potassium hydroxide, sodium carbonate, sodiumhydrogencarbonate, potassium carbonate, potassium hydrogencarbonate,sodium silicate, sodium methylsilicate, aqueous ammonia, ethylamine,diethylamine, dimethyl ethanolamine, tetramethylammonium hydroxide,tetraethylammonium hydroxide, choline, pyrrole, piperidine,1,8-diaza-bicyclo(5,4,0)-7-undecene, or the like. The concentration ofthe developer in the solution is from 0.001 wt % to 10 wt %, preferablyfrom 0.005 wt % to 5 wt %, and more preferably from 0.01 wt % to 1 wt %.

The backlight unit 20 is coupled to the second substrate 14 of theliquid crystal display element 10, and emits a light having a colortemperature ranging from 6,000 K to 20,000 K. The useful examples of thebacklight unit 20 include, but are not limited to, a white lightemitting diode, a trichrome fluorescent lamp, or a combination thereof.

In the light-emitting mechanism for the white light emitting diode usedas the backlight unit 20, blue light emitted from a light-emitting layerof a light-emitting die is absorbed by photoluminescent phosphor and isthen transferred into a light of other color. Some energy is lost duringthe transfer. When the color temperature of the backlight unit 20 islower than 6,000 K, the amount of the photoluminescent phosphor shouldbe increased. The extent of the energy lost due to the transfer isincreased, which results in decrease of the luminescent intensity.Therefore, it is difficult to enhance the luminance of the display inthe bright state, and the contrast is reduced. On the other hand, whenthe color temperature of the backlight unit 20 is higher than 20,000 K,the amount of the photoluminescent phosphor should be decreased. Theluminescent intensity of the red light is reduced and the brightness ofthe red light is too low.

In the case that the trichrome fluorescent lamp is used as the backlightunit 20, when the color temperature of the backlight unit 20 is lowerthan 6,000 K, the amount of red phosphor should be increased. Theluminescent intensity of red light is too high, which results in lightleakage in the dark state. Therefore, the contrast is reduced. On theother hand, when the color temperature of the backlight unit 20 ishigher than 20,000 K, the amount of the red phosphor should bedecreased. The luminescent intensity of the red light is reduced, andthe brightness of the red light is too low.

Therefore, as described above, the range of the color temperature of thebacklight unit 20 in the present invention is from 6,000 K to 20,000 K,preferably from 6,500 K to 19,000 K, and more preferably from 7,000 K to18,000 K.

When the white light emitting diode is used as the backlight unit 20, alight-emitting layer of a blue light emitting die is formed with afluorescence filter film containing the photoluminescent phosphor on thesurface thereof, or a package material of the blue light emitting diecontains the photoluminescent phosphor. The light emitting layer of theblue light emitting die is made of a nitride compound semiconductor, agroup III-V compound semiconductor, a group II-IV compoundsemiconductor, a group IV-VI compound semiconductor, or combinationsthereof, and has a main peak of luminescent spectrum ranging from 430 nmto 500 nm. Preferably, the light emitting layer of the blue lightemitting die is made of InGaN or GaN material in combination with yellowphosphor and/or green phosphor and/or red phosphor so as to obtain thebacklight unit 20 having the aforesaid desirable range of the colortemperature.

Specifically, the photoluminescent phosphor includes at least one yellowor green phosphor selected from a cerium activated aluminum garnetphosphor, an alkaline earth metal silicate phosphor, or a combinationthereof. When the photoluminescent phosphor is the yellow phosphor, thecerium activated aluminum garnet phosphor is a phosphor ofRE₃(Al,Ga)₅O₁₂:Ce, a phosphor of (Tb,Al)₅O₁₂:Ce, or a combinationthereof, wherein RE is Y, Gd, La, or combinations thereof. The alkalineearth metal silicate phosphor is a phosphor of AE₂SiO₄:Eu, a phosphor ofSr₃SiO₅:Eu²⁺, or a combination thereof, wherein AE is Sr, Ba, Ca, orcombinations thereof. When the photoluminescent phosphor is the greenphosphor, the cerium activated aluminum garnet phosphor is a phosphor ofRE₃ (Al,Ga)₅O₁₂:Ce, wherein RE is Y, Gd, La, or combinations thereof.The alkaline earth metal silicate phosphor is a phosphor of AE₂SiO₄:Eu,a phosphor of Ca₃Sc₂Si₃O₁₂:Ce, or a combination thereof, wherein AE isSr, Ba, Ca, or combinations thereof. Additionally, when thephotoluminescent phosphor is the green phosphor, Ca₃Sc₂O₄:Ce can also beused as the green phosphor.

Preferably, the photoluminescent phosphor can further include a redphosphor of a europium activated phosphor, a europium activated sulfidephosphor, a europium activated nitride phosphor, or combinationsthereof. The europium activated phosphor is Y₂O₃:Eu. The europiumactivated sulfide phosphor is Y₂O₂S:Eu, La₂O₂S:Eu, or a combinationthereof. The europium activated nitride phosphor is AE₂Si₅N₈:Eu²⁺,CaAlSiN₃:Eu²⁺, CaAlSiBN₃:Eu, or combinations thereof, wherein AE is Sr,Ba, Ca, or combinations thereof.

Specifically referring to FIG. 2, in the manufacturing of the whitelight emitting diode, a light-emitting die 21 and a substrate 22 areprepared. The light-emitting die 21 emits light having a primarywavelength of 460 nm. The substrate 22 has a recessed holding member 221defining a receiving space 23. The recessed holding member 221 has abottom portion electrically connected to an external power source. Thelight-emitting die 21 is mounted on and electrically connects to thebottom portion of the recessed holding member 221. Polysiloxane resincontaining the photoluminescent phosphor 241 is filled into thereceiving space 23 until that the polysiloxane resin is flush with thesubstrate 22. The polysiloxane resin is cured at 70° C. for 3 hours andthen at 150° C. for 1 hour so as to form a package layer 24 containingthe photoluminescent phosphor 241.

When the trichrome fluorescent lamp is used as the backlight unit 20,the trichrome fluorescent lamp includes a phosphor combination includinga blue phosphor, a green phosphor, and a red phosphor. If the amount ofthe blue phosphor is increased, the light emitted by the trichromefluorescent lamp is bluish white, and the color temperature of thebacklight unit 20 is increased. If the amount of the red phosphor isincreased, the light emitted by the trichrome fluorescent lamp isreddish white, and the color temperature of the backlight unit 20 isdecreased. In view of the color temperature, the blue phosphor isselected from Sr₅ (PO₄)₃Cl:Eu, (SrCaBa)₅ (PO₄)₃Cl:Eu, BaMg₂Al₁₆O₂₇:Eu,and combinations thereof, the green phosphor is selected from LaPO₄:Ce,LaPO₄:Tb, LaPO₄:CeTb, (CeTb)MgAl₁₄O₁₉, and combinations thereof, and thered phosphor is Y₂O₃:Eu. Preferably, the blue phosphor is in an amountranging from 20 to 55 wt %, the green phosphor is in an amount rangingfrom 20 to 55 wt %, and the red phosphor is in an amount ranging from 20to 45 wt % based on a total weight of the phosphor combination.

Color Liquid Crystal Display:

Referring once again to FIG. 1, as described above, the color liquidcrystal display device of the present invention includes the liquidcrystal display element 10 and the backlight unit 20.

The liquid crystal display element 10 includes the first substrate 13,the second substrate 14 spaced apart from the first substrate 13, thecolor filter 11 coupled to the first substrate 13, two alignment layers15 respectively disposed on the color filter 11 and the second substrate14 and facing toward each other, liquid crystal 12 disposed between thealignment layers 15, and two polarizers 16 respectively coupled to thefirst and second substrates 13, 14 and distal from the liquid crystal12. The first substrate 13 is a color filter side substrate, and thesecond substrate 14 is a thin film transistor side substrate. Thebacklight unit 20 is coupled to the second substrate 14 so as to formthe color liquid crystal display device.

The color liquid crystal display device of the present invention can beused with twisted nematic liquid crystal, super twisted nematic liquidcrystal, in-plane switching liquid crystal, vertical alignment liquidcrystal, optically compensated birefringence liquid crystal,ferroelectric liquid crystal, or the like.

EXAMPLES

The following examples are provided to illustrate the preferredembodiments of the invention, and should not be construed as limitingthe scope of the invention.

Synthesis of Alkali-Soluble Resin Synthesis Example B-1

A 1000 ml four-necked conical flask equipped with a nitrogen inlet, astirrer, a heater, a condenser and a thermometer was purged withnitrogen, and was added continuously with 45 parts by weight of2-methacryloylethoxy succinate monoester (referred to as HOMShereinafter), 15 parts by weight of styrene monomer (referred to as SMhereinafter), 10 parts by weight of dicyclopentenyloxyethyl acrylate(referred to as DCPOA hereinafter), 25 parts by weight of benzylmethacrylate (referred to as BzMA hereinafter), 5 parts by weight ofmethyl acrylate (referred to as MA hereinafter), and 200 parts by weightof ethyl 3-ethoxypropionate (referred to as EEP hereinafter, as asolvent).

The contents in the four-necked conical flask were stirred while thetemperature of an oil bath was raised to 100° C. 4 parts by weight of2,2′-azobis-2-methyl butyronitrile (referred to as AMBN hereinafter, asa polymerization initiator) dissolved in EEP was added into thefour-necked conical flask in five aliquots within one hour.

Polymerization was conducted at 100° C. for 6 hours. Polymerizationproduct was removed from the four-necked conical flask after thepolymerization was complete. The solvent was evaporated so as to obtainan alkali-soluble resin (B-1).

Synthesis Examples B-2 and B-3

Synthesis Examples B-2 and B-3 were conducted in a manner identical tothat of Synthesis Example 1 using the components, the amounts thereof,and the reaction conditions shown in Table 1.

TABLE 1 Synthesis Examples of alkali-soluble resin: Composition (partsby weight) Reaction Reaction Syn. Monomers for Polymerization InitiatorSolvent Feeding Temp. Time Ex.# HOMS MAA SM DCPOA BzMA PMI MA AMBN EEPmanner (° C.) (hrs) B-1 45 15 10 25 5 4 200 Continuously 100 6 B-2 35 1035 5 10 4 200 Continuously 100 6 B-3 25 20 5 10 30 5 4 200 Continuously100 6 Note: HOMS: 2-methacryloyloxyethyl succinate monoester MAA:methacrylic acid SM: styrene monomer DCPOA: dicyclopentenyloxyethylacrylate BzMA: benzyl methacrylate PMI: N-phenylmaleimide MA: methylacrylate AMBN: 2,2′-azobis-2-methyl butyronitrile EEP: ethyl3-ethoxypropionate

Preparation Examples of Red Photosensitive Resin Composition PreparationExample a

160 parts by weight of C.I. Pigment Red 242, 20 parts by weight of C.I.Pigment Red 89, 20 parts by weight of C.I. Pigment Yellow 150, 90 partsby weight of the alkali-soluble resin (B-1) obtained from SynthesisExample B-1, 10 parts by weight of the alkali-soluble resin (B-3)obtained from Synthesis Example B-3, 90 parts by weight ofdipentaerythritol hexaacrylate (referred to as C-1 hereinafter,manufactured by Toagosei), 10 parts by weight of TO-1382 (referred to asC-2 hereinafter, manufactured by Toagosei), 10 parts by weight of1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethylketo1-(O-acetyloxime) (referred to as D-1 hereinafter), parts by weight of2,2′-bis(2,4-dichlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole (referredto as D-2 hereinafter), 4 parts by weight of2,4-bis(trichloromethyl)-6-(p-methoxy)styryl-s-triazine (referred to asD-3 hereinafter), and 2,100 parts by weight of ethyl 3-ethoxypropionate(referred to as E-1 hereinafter, used as a solvent) were mixed using ashaker to obtain a red photosensitive resin composition.

Preparation Examples b to n

Preparation Examples b to n were conducted in a manner identical to thatof Preparation Example a using the components and the amounts thereofshown in Table 2.

TABLE 2 Preparation Examples a to n: Preparation Examples Components a bc d e f g h i j k l m n Pigments A-1 C.I. 140 60 180 pbw Pigment Red 166C.I. 160 120 100 80 40 20 200 100 100 Pigment Red 242 A-2 C.I. 40 80 100120 160 20 180 200 Pigment Red 89 C.I. 60 140 Pigment Red 177 A-3 C.I.100 100 165 Pigment Red 254 A-4 C.I. 15 20 20 20 85 Pigment Yellow 139C.I. 20 10 10 15 20 20 10 Pigment Yellow 150 Weight ratio (A-1)/(A-2)80/20 70/30 60/40 50/50 40/60 30/70 20/80 90/10 10/90 0/100 100/0 100/0100/0 Alkali-soluble B-1 90 90 90 90 90 90 90 90 resin B-2 90 90 90 9090 90 B-3 10 10 10 10 10 10 10 10 10 10 10 10 10 10 A compound C-1 90 80100 50 90 80 90 90 90 90 90 80 80 90 having an C-2 10 20 50 10 20 10 1010 10 10 20 20 10 ethylenic group Photoinitiator D-1 10 10 10 10 10 1010 10 10 10 10 10 10 10 D-2 4 4 4 4 4 4 4 4 4 4 4 4 4 D-3 4 4 4 4 4 4 44 4 4 4 4 4 Solvent E-1 2100 2200 1100 1000 900 1100 1100 2100 2200 E-22100 2200 1000 1100 1300 2100 2200 1000 1000 2100 Note: C-1:pentaerythritol triacrylate (manufactured by Toagosei) C-2: TO-1382(manufactured by Toagosei) D-1:1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethylketo1-(O-acetyloxime) D-2:2,2′-bis(2,4-dichlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole D-3:2,4-bis(trichloromethyl)-6-(p-methoxy)styryl-s-triazine E-1: ethyl3-ethoxypropionate E-2: propylene glycol methyl ether acetate

Preparation Example of Green Photosensitive Resin Composition

A green photosensitive resin composition was prepared in a manneridentical to that of Preparation Example a except the following wereused: 150 parts by weight of C.I. Pigment Green 58, 100 parts by weightof C.I. Pigment Yellow 150, 90 parts by weight of the alkali-solubleresin (B-1) obtained from Synthesis Example B-1, 10 parts by weight ofthe alkali-soluble resin (B-3) obtained from Synthesis Example B-3, 90parts by weight of the ethylenic compound (C-1), 10 parts by weight ofthe ethylenic compound (C-2), 8 parts by weight of the photoinitiator(D-1), 8 parts by weight of the photoinitiator (D-2), 4 parts by weightof the photoinitiator (D-3), and 2,100 parts by weight of the solvent(E-1).

Preparation Example of Blue Photosensitive Resin Composition

A blue photosensitive resin composition was prepared in a manneridentical to that of Preparation Example a except the following wereused: 240 parts by weight of C.I. Pigment Blue 15:6, 10 parts by weightof C.I. Pigment Purple 23, 90 parts by weight of the alkali-solubleresin (B-1) obtained from Synthesis Example B-1, 10 parts by weight ofthe alkali-soluble resin (B-3) obtained from Synthesis Example B-3, 90parts by weight of the ethylenic compound (C-1), 10 parts by weight ofthe ethylenic compound (C-2), 10 parts by weight of the photoinitiator(D-1), 5 parts by weight of the photoinitiator (D-3), 5 parts by weightof 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, and2, 100 parts by weight of the solvent (E-1).

Preparation of a Color Filter Preparation Example 11-a

The red photosensitive resin composition obtained in Preparation Examplea was spin-coated on a glass substrate, dried under a pressure of 100 mmHg for 30 seconds, and was pre-baked at a temperature of 80° C. for 3minutes to form a pre-baked film having a thickness of 2.5 μm. Thepre-baked film was exposed using a mask aligner (Canon PLA-501F, 300mJ/cm²), was immersed into a developer solution at a temperature of 23°C. for 2 minutes, was washed with water, and was post-baked at atemperature of 200° C. for 80 minutes to form a red pixel pattern. Theaforesaid procedure was repeated to form a green pixel pattern and ablue pixel pattern. A pixel layer having a thickness of about 2.0 μm wasobtained thereby.

An ITO (indium tin oxide) film was deposited on the pixel layer at atemperature of 235° C. under vacuum. The ITO film can be etched andformed with a wiring layout, if necessary. A color filter was obtainedthereby.

Preparation Examples 11-b to 11-n

Preparation Examples 11-b to 11-n were conducted in a manner identicalto that of Preparation Example 11-a using the red photosensitive resincompositions obtained in Preparation Examples b to n.

Preparation of a Liquid Crystal Display Element

Polyimide was applied on an ITO layer deposited on each of the substrateformed with the color filter and a substrate formed with a thin filmtransistor and was heated to form an alignment layer. The two substrateswere arranged to oppose each other with a spacer (cell gap). Theperipheral portions of the two substrates were joined together with asealing agent, liquid crystals were filled into the cell gap defined bythe surfaces of the substrates and the sealing agent, and an injectionhole was sealed up to form a liquid crystal cell. Then, a polarizer wasaffixed to the exterior sides of the liquid crystal cell to obtain theliquid crystal display element.

Preparation of a Backlight Unit Preparation Examples 20-1-1 to 20-1-6

A blue light-emitting die of InGaN (manufactured by Chi Mei LightingTechnology Corp., light-emitting wavelength of 460 nm) was mounted on arecessed holding member and was electrically connected to a bottomportion of the recessed holding member. Polysiloxane resin containingyellow phosphor and red phosphor in a blending ratio shown in Table 3was filled into a receiving space defined by the recessed holding memberuntil the polysiloxane resin was flush with the recessed holding member.The polysiloxane resin was cured to obtain a white light emitting diodeused as the backlight unit.

TABLE 3 Preparation Examples of a white light emitting diode used as abacklight unit Color Prep. temp. Ex. # Yellow phosphor Pbw Red phosphorpbw (K) 20-1-1 (SrBa)₂SiO₄: Eu 18 CaAlSiBN₃: Eu 2.5 3934 20-1-2(SrBa)₂SiO₄: Eu 17 CaAlSiBN₃: Eu 2 6050 20-1-3 Y₃(Al,Ga)₅O₁₂: Ce 15CaAlSiBN₃: Eu 2 11377 20-1-4 Y₃(Al,Ga)₅O₁₂: Ce 14 CaAlSiBN₃: Eu 1 1535020-1-5 Y₃(Al,Ga)₅O₁₂: Ce 13.2 Y₂O₃: Eu 0.9 19805 20-1-6 Y₃(Al,Ga)₅O₁₂:Ce 11 Y₂O₃: Eu 0.5 22260 Note: 1. pbw: parts by weight 2. light-emittingwavelength of (SrBa)₂SiO₄: Eu: 550-570 nm 3. light-emitting wavelengthof Y₃(Al,Ga)₅O₁₂: Ce: 520-550 nm 4. light-emitting wavelength ofCaAlSiBN₃: Eu: 650-670 nm 5. light-emitting wavelength of Y₂O₃: Eu:610-630 nm

Measurement of Color Temperature of a Backlight Unit:

CIE chromaticity coordinate value and brightness of a backlight unitwere determined using a colorimeter (manufactured by Otsuka ElectronicsCo., Model No. MCPD). Color temperature of the backlight unit could bedetermined from the chromaticity coordinate value and isotemperatureline.

Preparation Examples 20-2-1 to 20-2-6

Red phosphor of Y₂O₃:Eu, green phosphor of LaPO₄:Ce, Tb, and bluephosphor of (SrCaBa)₅(PO₄)₃Cl:Eu were blended together in a blendingratio shown in Table 4 to obtain a phosphor blend, which was mixed witha butyl acetate solution of nitrocellulose to obtain a suspension. Thesuspension was applied to an inner surface of a glass tube having aninner diameter of 32 mm and was dried to form a coating layer on theinner surface of the glass tube. The coating layer was baked at atemperature of 500° C. to form a trichrome fluorescent lamp of 40 W usedas the backlight unit. The color temperature of each of the trichromefluorescent lamps obtained in Preparation Examples 20-2-1 to 20-2-6 werealso shown in Table 4.

TABLE 4 Preparation examples of a trichrome fluorescent lamp used as thebacklight unit Blending ratio Color Prep. Red phosphor Green phosphorBlue phosphor temp. Ex. # (%) (%) (%) (K) 20-2-1 40 35 25 3512 20-2-2 3535 30 6105 20-2-3 34 33 33 10894 20-2-4 32 33 35 15536 20-2-5 31 32 3719780 20-2-6 30 30 40 22122 Red phosphor: Y₂O₃: Eu Green phosphor:LaPO₄: Ce,Tb Blue phosphor: (SrCaBa)₅(PO₄)₃Cl: Eu

Examples of Color Liquid Crystal Display Device Example 1

The liquid crystal display element made from the color filter obtainedin Preparation Example 11-a was coupled to the backlight unit obtainedin Preparation Example 20-1-2 to obtain a color liquid display device,which was evaluated according to the following evaluation methods. Theevaluation results are shown in Table 5-1.

Contrast Measurement:

Luminance of red light displayed by a color liquid crystal displaydevice at a bright state and at a dark state were measured using aluminance meter (manufactured by Topcon, Japan, Model No. BM-5A). Thevalue of contrast (R_(c)) can be obtained from a ratio of the luminanceat the bright state to the luminance at the dark state.

⊚: Rc≧2000 ◯: 1500≦Rc<2000 Δ: 1000≦Rc<1500 X: Rc<1000

CIE chromaticity coordinate value (x,y) and brightness (Y) of a colorliquid crystal display were determined using a colorimeter (manufacturedby Otsuka Electronics Co., Model No. MCPD). The brightness (Y) of redcolor displayed by the color liquid crystal display was used for thebrightness evaluation.

⊚: Y≧20 ◯: 15≦Y<20 Δ: 10≦Y<15 X: Y<5 Examples 2 to 8

Examples 2 to 8 were conducted in a manner identical to that of Example1 using the color filters and the backlight units shown in Table 5-1.The evaluation results of Examples 2 to 8 are also shown in Table 5-1.

Comparative Examples 1 to 11

Comparative Examples 1 to 11 were conducted in a manner identical tothat of Example 1 using the color filters and the backlight units shownin Table 5-2. The evaluation results of Comparative Examples 1 to 11 arealso shown in Table 5-2.

TABLE 5-1 Examples Components 1 2 3 4 5 6 7 8 Color filter 11-a 11-b11-c 11-d 11-d 11-e 11-f 11-g Weight ratio of 80/20 70/30 60/40 50/5050/50 40/60 30/70 20/80 (A-1)/(A-2) Backlight unit 20-2-2 20-2-3 20-2-420-2-5 20-1-2 20-1-3 20-1-4 20-1-5 Color temp. of 6105 10894 15536 197806050 11377 15350 19805 backlight unit results Contrast ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯Brightness ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚

TABLE 5-2 Comparative examples Components 1 2 3 4 5 6 7 8 9 10 11 Colorfilter 11-b 11-h 11-j 11-l 11-n 11-d 11-c 11-i 11-k 11-m 11-e Weightratio 70/30 90/10 0/100 100/0 — 50/50 60/40 10/90 100/0 100/0 40/60 of(A-1)/(A-2) Backlight unit 20-2-1 20-2-2 20-2-3 20-2-4 20-2-5 20-2-620-1-1 20-1-2 20-1-3 20-1-4 20-1-6 Color temp. of 3512 6105 10894 1553619780 22122 3934 6050 11377 15350 22260 backlight unit results ContrastΔ Δ X X X X Δ X X X X brightness X X X X X Δ X Δ X X Δ

As shown in Table 5-1, a color liquid crystal display device having highbrightness and high contrast can be obtained when a weight ratio of(A-1) an azo-based red pigment to (A-2) an anthraquinone-based redpigment is controlled to be within a range from 20/80 to 80/20 and acolor temperature of a backlight unit is controlled to be within a rangefrom 6,000 K to 20,000 K.

While the present invention has been described in connection with whatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation andequivalent arrangements.

What is claimed is:
 1. A color liquid crystal display device,comprising: a liquid crystal display element including a color filterhaving a red filter segment, a green filter segment, and a blue filtersegment, said red filter segment being prepared from a redphotosensitive resin composition which includes a pigment combination,an alkali-soluble resin, a compound having an ethylenic group, and aphotoinitiator, said pigment combination including an azo-based redpigment and an anthraquinone-based red pigment, a weight ratio of saidazo-based red pigment to said anthraquinone-based red pigment rangingfrom 20/80 to 80/20; and a backlight unit coupled to said liquid crystaldisplay element and having a color temperature ranging from 6,000 K to20,000 K.
 2. The color liquid crystal display device as claimed in claim1, wherein said weight ratio of said azo-based red pigment to saidanthraquinone-based red pigment ranges from 30/70 to 80/20.
 3. The colorliquid crystal display device as claimed in claim 1, wherein saidazo-based red pigment is selected froma group consisting of C.I. PigmentRed 144, C.I. Pigment Red 166, C.I. Pigment Red 214, C.I. Pigment Red220, C.I. Pigment Red 221, C.I. Pigment Red 242, C.I. Pigment Red 248,C.I. Pigment Red 262, and combinations thereof.
 4. The color liquidcrystal display device as claimed in claim 1, wherein saidanthraquinone-based red pigment is selected from a group consisting ofC.I. Pigment Red 83, C.I. Pigment Red 89, P.I. Pigment Red 177, andcombinations thereof.
 5. The color liquid crystal display device asclaimed in claim 1, wherein said pigment combination further includes ayellow pigment selected from a group consisting of an isoindole-basedyellow pigment, a quinaphthalone-based yellow pigment, ananthraquinone-based yellow pigment, and combinations thereof.
 6. Thecolor liquid crystal display device as claimed in claim 5, wherein saidyellow pigment is said quinaphthalone-based yellow pigment.
 7. The colorliquid crystal display device as claimed in claim 6, wherein saidquinaphthalone-based yellow pigment is C.I. Pigment Yellow
 150. 8. Thecolor liquid crystal display device as claimed in claim 1, wherein saidbacklight unit is selected from a group consisting of a white lightemitting diode, a trichrome fluorescent lamp, and a combination thereof.9. The color liquid crystal display device as claimed in claim 8,wherein said backlight unit is said white light emitting diode includinga light emitting layer having a main peak of luminescent spectrumranging from 430 nm to 500 nm, and a photoluminescent phosphor, saidlight emitting layer being made of a material selected from a groupconsisting of a nitride compound semiconductor, a group III-V compoundsemiconductor, a group II-IV compound semiconductor, a group IV-VIcompound semiconductor, and combinations thereof.
 10. The color liquidcrystal display device as claimed in claim 9, wherein saidphotoluminescent phosphor includes a yellow or green phosphor selectedfrom a group consisting of a cerium activated aluminum garnet phosphor,an alkaline earth metal silicate phosphor, and a combination thereof.11. The color liquid crystal display device as claimed in claim 10,wherein said photoluminescent phosphor is a yellow phosphor, said ceriumactivated aluminum garnet phosphor being selected from a groupconsisting a phosphor of RE₃(Al,Ga)₅O₁₂:Ce, a phosphor of(Tb,Al)₅O₁₂:Ce, and a combination thereof, wherein RE is selected from agroup consisting of Y, Gd, La, and combinations thereof, said alkalineearth metal silicate phosphor being selected from a group consisting ofa phosphor of AE₂SiO₄:Eu, a phosphor of Sr₃SiO₅:Eu²⁺, and a combinationthereof, wherein AE is selected from a group consisting of Sr, Ba, Ca,and combinations thereof.
 12. The color liquid crystal display device asclaimed in claim 10, wherein said photoluminescent phosphor is a greenphosphor, said cerium activated aluminum garnet phosphor being aphosphor of RE₃(Al,Ga)₅O₁₂:Ce, wherein RE is selected from a groupconsisting of Y, Gd, La, and combinations thereof, said alkaline earthmetal silicate phosphor being selected from a group consisting of aphosphor of AE₂SiO₄:Eu, a phosphor of Ca₃Sc₂Si₃O₁₂:Ce, and a combinationthereof, wherein AE is selected from a group consisting of Sr, Ba, Ca,and combinations thereof.
 13. The color liquid crystal display device asclaimed in claim 9, wherein said photoluminescent phosphor includes agreen phosphor selected from a group consisting of RE₃ (Al,Ga)₅O₁₂:Ce,AE₂SiO₄:Eu, Ca₃Sc₂Si₃O₁₂:Ce, Ca₃Sc₂O₄:Ce, and combinations thereof,wherein RE is selected from a group consisting of Y, Gd, La, andcombinations thereof, and wherein AE is selected from a group consistingof Sr, Ba, Ca, and combinations thereof.
 14. The color liquid crystaldisplay device as claimed in claim 10, wherein said photoluminescentphosphor further includes a red phosphor selected from a groupconsisting of a europium activated phosphor, a europium activatedsulfide phosphor, a europium activated nitride phosphor, andcombinations thereof.
 15. The color liquid crystal display device asclaimed in claim 14, wherein said europium activated phosphor isY₂O₃:Eu, said europium activated sulfide phosphor being selected from agroup consisting of Y₂O₂S:Eu, La₂O₂S:Eu, and combinations thereof, saideuropium activated nitride phosphor being selected from a groupconsisting of AE₂Si₅N₈:Eu²⁺, CaAlSiN₃:Eu²⁺, CaAlSiBN₃:Eu, andcombinations thereof, wherein AE is selected from a group consisting ofSr, Ba, Ca, and combinations thereof.
 16. The color liquid crystaldisplay device as claimed in claim 8, wherein said backlight unit issaid trichrome fluorescent lamp which includes a phosphor combinationincluding a blue phosphor, a green phosphor, and a red phosphor.
 17. Thecolor liquid crystal display device as claimed in claim 16, wherein saidblue phosphor is selected from a group consisting of Sr₅ (PO₄)₃Cl:Eu,(SrCaBa)₅ (PO₄)₃Cl:Eu, BaMg₂Al₁₆O₂₇:Eu, and combinations thereof, saidgreen phosphor is selected from a group consisting of LaPO₄:Ce,LaPO₄:Tb, LaPO₄:CeTb, (CeTb)MgAl₁₄O₁₉, and combinations thereof, andsaid red phosphor is Y₂O₃:Eu.
 18. The color liquid crystal displaydevice as claimed in claim 16, wherein said blue phosphor is in anamount ranging from 20 to 55 wt %, said green phosphor is in an amountranging from 20 to 55 wt %, and said red phosphor is in an amountranging from 20 to 45 wt % based on a total weight of said phosphorcombination.